This study investigated the effectiveness of guided inquiry instructional strategy on upper basic science students’ academic performance in Otukpo LGA, Benue State. Quasi-experimental research design, specifically, pre-test post-test non-equivalent, non-randomized control group design was adopted. A sample of 72 students drawn from a population of 1,832 was used for the study. Two research questions were raised and answered in the study using mean and standard deviation while two hypotheses formulated were tested using Analyisis of Covariance (ANCOVA)

at 0.05 level of significant. The instrument for data gathering was a validated Basic Science Performance Test (BSPT). It had reliability coefficient of 0.91 determined using Richard Kuderson 20 (K-R20) method. Students in both groups were given pre-test before instruction.

During the instruction, the same content was presented to the two groups for a period of four weeks and thereafter, a post-test was administered. The findings of the study revealed that the students in guided inquiry strategy outperformed their counterparts in demonstration method.

[F(1,69) = 15.915; p = 0.000 < 0.05], the results also showed that gender had no significant effect on mean performance scores of students taught Basic Science using guided inquiry strategy [ F(1,35) = 0.223; p = 0.640 > 0.05]. Based on the findings, it was recommended among others that guided inquiry strategy should be employed for teaching Basic science to enhance their performance.